Shingles for roofing and siding applications are typically stored in stacks or pallets. These pallets may be exposed to high temperature environments, such as construction sites or storage yards that can receive direct sun for 2 to 12 hours per day. Most conventional shingles contain a layer of adhesive applied to the front surface of each shingle. The adhesive is typically temperature sensitive and will activate when a threshold temperature is reached, such as 20 to 60° F. higher than the expected ambient temperature where the shingles are to be used. When shingles are applied during building construction, solar heat will activate the adhesive and seal the shingles together. However, when pallets of shingles are left in high temperature environments for extended periods of time, solar energy may prematurely activate the adhesive, causing the shingles to adhere to each other.
Previous attempts to remedy this problem have included covering the pallet of shingles with a cardboard or paper wrapper in order to protect the shingles from solar heat. However, these cardboard or paper wrappers often fail to maintain an appropriate ambient temperature within the shingle pallet. Alternately, the pallet can be covered with a heat reflective plastic wrapper or shroud. These plastic wrappers are not only costly and time consuming but can actually increase the internal temperature within the pallet, thus promoting unwanted shingle adhesion.
Other solutions have comprised applying a film to the adhesive coating to prevent sealing of the shingles until just prior to application on a roof. Under certain pallet aging conditions, however, the adhesion of the film can increase so that when the shingle is pulled from the pallet, the film tends to debond from the upper shingle and remain partially or entirely on the adhesive layer of the lower shingle. Alternately, the adhesive strip can debond entirely from both surfaces and become free. These partially or completely debonded films are a nuisance for shingle installers as well as a source of litter at the construction site.